1 2 #ifndef lint 3 static char vcid[] = "$Id: dgedi.c,v 1.2 1996/03/04 05:16:18 bsmith Exp bsmith $"; 4 #endif 5 6 /* 7 This file creating by running f2c 8 linpack. this version dated 08/14/78 9 cleve moler, university of new mexico, argonne national lab. 10 11 Computes the inverse of a matrix given its factors and pivots 12 calculated by Linpack_DGEFA(). 13 */ 14 15 #include "petsc.h" 16 17 int Linpack_DGEDI(Scalar *a,int n,int *ipvt,Scalar *work) 18 { 19 int i__2,kb, kp1, nm1,i, j, k, l, ll,kn,knp1,jn; 20 Scalar t, *aa,*ax,*ay,tmp; 21 22 --work; 23 --ipvt; 24 a -= n + 1; 25 26 /* compute inverse(u) */ 27 28 for (k = 1; k <= n; ++k) { 29 kn = k*n; 30 knp1 = kn + k; 31 a[knp1] = 1.0 / a[knp1]; 32 t = -a[knp1]; 33 i__2 = k - 1; 34 aa = &a[1 + kn]; 35 for ( ll=0; ll<i__2; ll++ ) aa[ll] *= t; 36 kp1 = k + 1; 37 if (n < kp1) continue; 38 ax = aa; 39 for (j = kp1; j <= n; ++j) { 40 jn = j*n; 41 t = a[k + jn]; 42 a[k + jn] = 0.; 43 ay = &a[1 + jn]; 44 for ( ll=0; ll<k; ll++ ) { 45 ay[ll] += t*ax[ll]; 46 } 47 } 48 } 49 50 /* form inverse(u)*inverse(l) */ 51 52 nm1 = n - 1; 53 if (nm1 < 1) { 54 return 0; 55 } 56 for (kb = 1; kb <= nm1; ++kb) { 57 k = n - kb; 58 kn = k*n; 59 kp1 = k + 1; 60 aa = a + kn; 61 for (i = kp1; i <= n; ++i) { 62 work[i] = aa[i]; 63 aa[i] = 0.; 64 } 65 for (j = kp1; j <= n; ++j) { 66 t = work[j]; 67 ax = &a[j * n + 1]; 68 ay = &a[kn + 1]; 69 for ( ll=0; ll<n; ll++ ) { 70 ay[ll] += t*ax[ll]; 71 } 72 } 73 l = ipvt[k]; 74 if (l != k) { 75 ax = &a[kn + 1]; 76 ay = &a[l * n + 1]; 77 for ( ll=0; ll<n; ll++ ) { 78 tmp = ax[ll]; 79 ax[ll] = ay[ll]; 80 ay[ll] = tmp; 81 } 82 } 83 } 84 return 0; 85 } 86 87